Administrators of large numbers of machines (including both physical and virtual machines) often desire to communicate with a monitoring system that monitors the performance of these machines in order to obtain the real-time system state updates. Although most conventional performance-monitoring systems are capable of sending alerts in the form of emails or SMS (short message service) messages to an administrator, such communications are only in one direction and are not in real time. Furthermore, the existing performance-monitoring systems cannot easily facilitate multi-party communication sessions, which are often useful for collective efforts in system-error diagnosis and emergency responses.